Tensions rose between Kosovo and Serbia Tuesday after police in Kosovo confronted and arrested Serbs as part of an anti-smuggling mission in the country's northern region.
The action sparked a swift response from neighbouring Serbia, which does not recognise Kosovo as a state.
Serbia put its forces on alert after the operation, and Serbian President Aleksandar Vucic said that Serbia's military was prepared to defend Serbs in Kosovo. The northern municipalities in Kosovo are mainly populated by Serbs who support Belgrade over Pristina.
Kosovo's prime minister, on the other hand, insisted that it was just a police operation.
"I confirm that the operation is about law enforcement and nothing else. I call Serbs in the north to stay calm and respect the law," Kosovo Prime Minister Ramush Haradinaj said.
But at least 19 people were arrested, and two UN officials were detained in an operation that saw both police and Serbs wounded.
"The UN mission in Kosovo said that it is concerned by the developments in Northern Kosovo today, including the detention of two UN staff members who were carrying out their duties by the Kosovo police," said Farhan Haq, deputy spokesperson for the UN Secretary-General. Haq said that both UN staff members were transferred to a hospital for "treatment of their injuries."
Cross-border smuggling has increased in the northern Serb-majority municipalities. Kosovo implemented a 100 per cent tariff on goods from Serbia last year after Serbia blocked Kosovo from joining Interpol.
Kosovo's foreign minister Behgjet Pacolli said it would not be the last police operation in Kosovo, according to the AP.
"We are fighting organized crime," Pacolli said.
The Russian foreign ministry was quick to call the event a "provocation." Russia is another country that does not recognise Kosovo's independence.
Kosovo is majority Albanian but was a region of Serbia until declaring its independence in the 1990s. The ensuing violent war killed more than 13,000 people and only ended after a NATO air campaign in 1999.
Kosovo became a self-governed territory under the United Nations and declared its independence once again in 2008. It has been recognised by more than 100 countries.
Read more about the history of Kosovo-Serbia relations here and watch more in the video player above.